1. Technical Field
The present invention relates to a musical tone reproducing apparatus capable of changing tone color, and a portable terminal apparatus having the musical tone reproducing apparatus.
2. Background Art
Conventional musical tone reproducing apparatuses include ones that generate musical tones using hardware. Such a musical tone reproducing apparatus is constructed such that the tone color of reproduced musical tones can be changed.
An example of the construction of such a musical tone reproducing apparatus is shown in FIG. 10, and a description will now be given of the changing of the tone color. In FIG. 10, a CPU (central processing unit) 110 reads sequence data such as MIDI (musical instrument digital interface) data or SMAF (synthetic music mobile application format) data out from a RAM (random access memory) 111, and supplies the sequence data to a tone generator hardware section 115. The tone generator hardware section 115 reproduces the sequence data supplied from the RAM 111, and accordingly outputs musical tone signals to a speaker 134. The tone generator hardware section 115 is comprised of a tone color parameter storage region 130, and a data processing section 133 that carries out a musical tone reproducing process. The tone color parameter storage region 130 is comprised of registers or regions reserved in the RAM 111.
In the musical tone reproducing apparatus constructed as above, when changing the tone color of a musical tone to be reproduced, the CPU 110 gives a tone color changing command to the tone color parameter storage region 130, and also reads a tone color parameter for the tone color to be changed to out from the RAM 111, and writes the tone color parameter into the tone color parameter storage region 130. Once musical tone reproduction timing been has reached, the data processing section 133 reads the tone color parameter for the tone color to be changed to out from the tone color parameter storage region 130, and carries out musical tone reproduction with a tone color changed using the tone color parameter. Note that much sequence data and a plurality of tone color parameters (a tone color parameter group) can be stored in the RAM 111.
In such a conventional musical tone reproducing apparatus, when changing the tone color, the CPU 110 reads the tone color parameter for the tone color to be changed to out from the RAM 111 and transfers the tone color parameter to the tone generator hardware section 115 as described above. In this case, because the data bus width of the tone generator hardware section 115 is approximately 8 bits, the bit width of the RAM or registers constituting the tone color parameter storage region 130, i.e. the bit width of the stored data, is also limited to being approximately 8 bits. However, one or more tone color parameters for one channel required when the data processing section 133 carries out the tone reproducing process for one channel are comprised of many bits, specifically several tens of bits. Consequently, with a RAM or registers having a bit width of 8 bits, it has been necessary for the one or more tone color parameters for one channel required when the data processing section 133 carries out the tone reproducing process for one channel to be read out divided into a plurality of times each of 8 bits. As a result, a problem has arisen that a long time is required to read out the tone color parameter for a tone color to be changed to from the tone color parameter storage region 130 and set the tone color parameter in the data processing section 133, and hence the processing time becomes long.
If the processing time becomes long as described above, then a break may occur in sound generation. To resolve this, one can envisage increasing the operating speed of the RAM or registers constituting the tone color parameter storage region 130. However, there has been a problem that if the operating speed of the RAM or registers is increased, then the electric power consumption thereof increases, and hence a battery that is used to operate a portable terminal apparatus in which the musical tone reproducing apparatus is installed is used up quickly. Moreover, every time a tone color is to be changed, the CPU 110 must transfer the tone color parameter for the tone color to be changed to from the RAM 111 to the tone generator hardware section 115, and hence there has been a problem that the amount of data transfer between the tone generator hardware section 115 and the CPU 110 increases.
Furthermore, if the tone color parameter storage region 130 is comprised of registers exclusively for this purpose, then reading out from a freely chosen number of registers can be carried out simultaneously, but the tone color parameter storage region 130 becomes a region exclusively for tone color parameters, and hence a problem arises that if the tone color parameter storage region 130 is also used for general-purpose data having a width of 8 bits other than tone color parameters, then the efficiency of usage of the tone color parameter storage region 130 as a memory becomes poor.
Moreover, if the tone color parameter storage region 130 is comprised of a RAM having a large bit width, then a tone color parameter having a large bit width can be read out at a time, but the tone color parameter storage region 130 becomes a region exclusively for tone color parameters, and hence a problem again arises that if the tone color parameter storage region 130 is also used for general-purpose data having a width of 8 bits other than tone color parameters, then the efficiency of usage of the tone color parameter storage region 130 as a memory becomes poor.
It is thus an object of the present invention to provide a musical tone reproducing apparatus which stores tone color parameters in a general-purpose storage means, to thereby shorten the time taken for a tone color changing process, and a portable terminal apparatus having the musical tone reproducing apparatus.